The most important move in epidemiology is from a comparison of counts to statements of causality: if we accept some factor as causal then we assume that we can alter the frequency of disease if we alter that factor. To make this move, we need concepts and strategies. The main objective is to decide whether or not a given factor is a cause of a disease. A cause makes something happen, i.e., causes or prevents disease. Understanding causes enables us to change things, for example, if we want to to diminish the frequency of coronary heart disease. Even though philosophers have talked a long time, and still talk, about causes, epidemiologists seem to stick to a decace-old pragmatic definition of a cause as “something that if you take it away, will lower the frequency of a disease”. This view foreshadows the current dominating philosophy of thinking about causes in medical statistics and epidemiology, which is based on potential outcomes and counterfactual thinking.

Vineis P (2003) Causality in epidemiology. . In History of epidemiological methods and concepts , Morabia A (ed). Birkhäuser: Basel , pp337-350. Older version in SPM.

Stellman SD (2003) Issues of causality in the history of occupational epidemiology. In History of epidemiological methods and concepts , Morabia A (ed). Birkhäuser: Basel , pp. 275-290. Older version in SPM.